Great information, above. Thanks all, especially Ed / FlaHeatWave and Dave. I had the Progressive Monotube and 12" Suspension Technologies on the SERG3 and loved them but could see that some might find them harsh. The front of my '15 Road Glide Ultra seems very good but not great. The air shocks will have to go in favor of HD adjustables Ed described or Suspension Technologies 13". I'm too cheap to spend more than that on a HOG.
BTW, I'm sure most of you know this already but no one mentioned it so... there is only a 9/16th" ride height difference between a 12" and 13" shock ride height due to the angle of the shocks from vertical.
The front on the 15 SERGU is better than the front on my 13 SERK and better than the front on my 12 SERG was.
I hated this 15 SERGU the first time I rode it in the curves, the rear felt loose and like it would wash out. Had planned to put 12" on it vice the 13" Ohlin rep convinced me that the 13 was a better choice. Said the bike was designed for it, as were the bikes I had with 12" were designed for the 13". He went on to say turn in would be better, lean angle would be better, and it had more travel, so less likely to bottom out.
These Ohlins HD159 are great, and the bike now handles better than my 09 SERG did with progressive mono tubes up front and 944s in the back, better than my 12 SERG did, which like my current 13 SERK has 12 hd premium low hand adjustable shocks and stock front.
Thing I like about the Ohlin rear, they are rebuildable for 250 dollars. They will not go with the bike when its traded. I also like I can soften them up for ridding interstate, and then back firmer for the curves with out a tool.
I am seriously looking at adding them to my SERK, or the ones with remote as I am keeping the 110th anniversary bike, as I have a 100th also.